1.5 AS 90944 Demonstrate understanding of aspects of Acids and Bases (4 credits)
ATOMIC STRUCTURE
NCEA PAST EXAM QUESTIONS on Atomic structure
(a) Complete the table below.
(b) Write the formulae for the following ionic compounds. Use the table of ions in your resource booklet.
(i) Silver fluoride
(ii) Potassium sulfate
(iii) Calcium nitrate
(c) Sodium burns in oxygen gas, O2, to form sodium oxide, Na2O.
(i) Explain how the Na and O atoms form Na+ and O2– ions, in terms of their groups in the periodic table, electron arrangement, AND number of protons.
(ii) Justify the ratio of Na+ and O2– ions in the formula Na2O, in terms of the electrons lost or gained, and
the charge on each ion. Include an explanation of the type of bonding between the Na+ and O2– ions.
The diagrams below show models of three different atoms.
(a) Each of these atoms can form ions, as listed below.
• Explain why each of the ions has the charge it does, in terms of electron arrangement and number of protons.
• Ions are charged atoms. Explain how each of the ions below reached the charge shown.
You should discuss particles gained or lost by the atoms involved, and the reasons for this.
Aluminium ion, Al3
Sulfide ion, S2–
Chloride ion, Cl–
(b) Explain why an ionic bond would not form between a sulfide ion and a chloride ion
In your answer you should:
• describe an ionic bond
• refer to charges and electron arrangements of the ions involved.
(i) Calcium chloride
(ii) Sodium nitrate
(iii) Zinc nitrate
(b) Complete the table below for the ions formed by magnesium, aluminium, and oxygen. Use the periodic table in your Resource Booklet to help you.
(c) The formula for magnesium oxide is MgO. The formula for aluminium oxide is Al2O3. Explain why the two formulae are different. In your answer:
• consider the ratio of ions in each formula and explain how the ratio is related to the charge on the ions
• relate the ratio of ions in the formula to the number of electrons lost or gained by each atom.
F–, Ne, and Mg2+have the same electron arrangement.
(a) Complete the table below
(b) Compare the atomic structure of F–, Ne, and Mg2+In your answer you should:
• describe the difference between an atom and an ion
• explain the charges on F–, Ne, and Mg2+in terms of electron arrangement and number of protons
• relate the position of F–, Ne, and Mg2+on the periodic table to the charges and electron arrangement
• explain why all three have the same electron arrangement.
a) State the charges of ALL three ions, Ca2+, F- and K+ in terms of electron arrangement and number of protons.
b) Use their positions on the periodic table to explain why two of the atoms form ions with the same charge, AND two of the atoms form ions with the same electron arrangement.
a) Explain why the ions formed by sodium and oxygen both have the same electron arrangement. In your answer you should:
• describe an ion
• describe the atomic structures of a sodium ion and an oxide ion
• state the charge on the sodium ion and the oxide ion
• explain the charges on both ions in terms of electron arrangement and number of protons.
b) Element X is between numbers 11 and 18 on the Periodic Table. An atom of element X forms an ion. This ion combines with the hydroxide ion to form a neutral compound, X(OH)3. Determine what element X is and justify your answer. In your answer you should:
• consider the ratio of X ions to hydroxide ions
• use the formula X(OH)3 to determine the charge of the X ion
• explain how you would use the Periodic Table in your Resource Booklet to find out which group element X is in
• name element X.
a) Magnesium and calcium atoms both form ions with a charge of +2. Magnesium atoms form Mg2+ ions, and calcium atoms form Ca2+ ions.
Explain why magnesium and calcium atoms form ions with the same charge of +2. In your answer, you should:
define an ion
explain why atoms form ions
identify the group on the periodic table where the two atoms are found
explain why both magnesium and calcium ions have a charge of +2.
b) Sodium and beryllium atoms form ions with different charges. Complete the table below.
c) Explain why the ions in sodium hydroxide combine to give the formula NaOH but the ions in beryllium hydroxide combine to give the formula Be(OH)2.
In your answer, you should:
compare the charges on the individual ions found in the compounds sodium hydroxide and beryllium hydroxide
explain why the ions combine in the ratios the way they do to form the compounds NaOH and Be(OH)2.
d) Explain why Li is a neutral atom. In your answer, you should fully describe its atomic structure and state the electron configuration.
Aluminium reacts with oxygen to form aluminium oxide. The formula of aluminium oxide contains two aluminium ions and three oxide ions. Discuss why the formula has two aluminium ions and three oxide ions. In your answer you should:
• State the formula for aluminium oxide.
• State the electron configuration of the aluminium atom, the oxygen atom, the aluminium ion, and the oxide ion.
• Use the electron configurations and numbers of electrons lost or gained when forming ions to justify the formula of aluminium oxide.
You may support your answer with diagrams.
a) Explain why carbon (C12) is a neutral atom. You should describe the atomic structure, and state the electron configuration.
b) Explain how the particles within an atom contribute to its overall mass.
c) Discuss how the mass of nitrogen (N13) compares with carbon (C12).
a) Oxygen atoms are made of protons, neutrons, and electrons. One type of oxygen atom can be represented as 818O.
i) Draw a diagram to show the arrangement of the electrons, protons, and neutrons within the above oxygen atom:
ii) Explain, with reference to the diagram, why the atom is neutral.
b) Use the table of ions in the Resource Booklet to fill in the missing name or formula for each of the compounds below.
c) Both potassium and magnesium form compounds with hydroxide ions.
i) Complete the table below for potassium and magnesium:
ii) Discuss why potassium hydroxide has the formula KOH, while magnesium hydroxide has the formula Mg(OH)2. Refer to:
• the information in part (i)
• the changes in the electron arrangements of potassium and magnesium when they react.
a) The element potassium can be represented as shown below.
i) How many protons, electrons and neutrons are in the element potassium shown above?
ii)Name the two particles found in the nucleus.
iii) The electron arrangement for the element carbon can be written 2, 4 Write the electron arrangement for the element potassium
b)i) Give the formula of zinc oxide potassium sulfate calcium hydrogen carbonate
ii) Name the following compounds Cu(OH)2 PbS MgCl2
c)i) State the charge on the iron ion in the compounds Fe2O3 FeCl2 Fe2(CO3)3
ii) Explain why the charge on the ion of element X in X(OH)2 is 2+.
The diagram below represents a model of a magnesium atom
The symbols in the diagram above represent the proton, electron and neutron.
a) Write the appropriate symbol from the diagram and what it represents - proton, electron or neutron
b) i) Using similar symbols, draw a diagram that shows a sodium atom
ii) Discuss the similarities and differences between a sodium atom and a sodium ion. You should consider the number of protons, electrons and neutrons, and the charge of each particle.
c) Name the compound Pb(NO3)-2 Refer to the Table of Ions in the Resource Booklet
d) Write the formula for potassium sulfide
e) i) How many atoms are there in Al(OH)3?
ii) How many atoms are there in 2Al(OH)3?
a) The diagram below can be used to represent the arrangement of electrons in levels around the nucleus of a sodium atom.
i) The atomic number of sodium is 11. How many protons are there in the nucleus of the neutral atom?
ii) How many neutrons are there in a sodium atom with a mass number of 23?
iii) How many electrons does a sodium atom lose to form a sodium ion?
b) A neutral oxygen atom has 8 electrons in the arrangement 2,6.
i) What is the atomic number of oxygen?
ii) How many electrons does oxygen gain to form an oxide ion?
iii) Draw a diagram like the one above for the arrangement of electrons around the nucleus of an oxide ion.
c) The formula of aluminium oxide is Al2O3. Explain why the formula has two aluminium atoms for every three oxygen atoms.
d) Use the table of ions in the Resource Booklet to work out the formulae for the following compounds.
f) Refer to the positions of oxygen and fluorine in the Periodic Table provided in the Resource Booklet. Comparing oxygen and fluorine, discuss how the electron arrangement, the atoms’ positions in the Periodic Table and the charges on their ions are related.
a) Complete the table below by putting the appropriate numbers in the boxes (i) – (vi).
b) The electron arrangement for nitrogen (N) is 2,5. Write the electron arrangement for: Li P Mg2+
c) Compare the positions of sodium (Na), potassium (K) and rubidium (Rb) on the Periodic Table.
i) What is the charge on a rubidium ion? (ii) Explain your answer.
d) i) How many atoms of oxygen are there in the formula Mg(HCO3)2? What is the total number of atoms in the formula?
ii) Using the Table of Ions provided in your Resource Booklet, write formulae for: calcium oxide, copper hydroxide, sodium carbonate iii) Name each of these compounds: MgO, Na2S, Ca(NO3)2 e) The doctor told Miriam she was tired and pale because she was low in iron. The iron tablets Miriam was given to take did not look like the iron nails they used in woodwork. Discuss how the chemical differences between the iron in the tablets and the iron in the nails are related to their uses.
EXTRA HELP: a straightforward animation explaining the formation of NaCl, a video too
EXTRA HELPquestions on ions to help you visualise and describe ionic charges clearly
INTERACTIVE animation to practice creating ionic compounds
RE-INFORCE and EXTEND your thinking and understanding of ionic bonding, with answers too
THINKING SKILLS: test your logical thinking skills and knowledge of atoms of ions on the Alien Periodic table, with answers too
PROPERTIES AND USES OF ACIDS AND BASES
NCEA PAST EXAM QUESTIONS on Properties and Uses of Acids and Bases
1) Write a word equation AND a balanced symbol equation for the reaction between calcium carbonate and hydrochloric acid.
2) A student has three unlabelled beakers each containing a colourless liquid. One contains water, one contains a solution of baking soda (sodium hydrogen carbonate), and one contains white vinegar (a solution of ethanoic acid).
To work out which liquid is which, the student put a drop from each beaker onto a piece of blue litmus paper and a piece of red litmus paper. She then added universal indicator to each beaker. The following results were obtained:
(a) Complete the last column of the table above to identify the three liquids.
(b) Use the information in the table to show how each of the liquids can be identified. In your answer you should:
• use all of the observations for each beaker
• state the approximate pH from the colour of the universal indicator.
(c) Another student was given two beakers (Beaker 4 and Beaker 5) each containing different liquids. The liquid in Beaker 4 had a pH of 1. The liquid in Beaker 5 had a pH of 6. Discuss which liquid is more acidic and how you know this. In your answer you should:
• use the pH to determine which liquid is more acidic
• compare the amount of hydrogen ions AND hydroxide ions in Beaker 4 (pH 1) with the amount of hydrogen ions AND hydroxide ions in Beaker 5 (pH 6).
3) A beaker contains sodium hydroxide solution and 5 drops of universal indicator. Sulfuric acid was added to the beaker until no more changes were observed.
(a) Write a word equation AND a balanced symbol equation for the reaction between sulphuric acid and sodium hydroxide.
(b) Describe how the indicator colour changes as the sulfuric acid is added to the beaker, AND explain what this tells you about the changing pH of this solution.
(c) Explain the relationship between the changing pH of the solution and the ions in the solution as the sulfuric acid is added to the beaker.
Potassium hydroxide (KOH) was added to a solution of sulfuric acid containing universal indicator until no further change was observed. The experiment was repeated, but a piece of red litmus paper and a piece of blue litmus paper were each dipped into the solution after each 5 mL of potassium hydroxide was added. The results of the experiments are shown in the table below.
(a) Write a word equation AND a balanced symbol equation for the reaction between sulfuric acid and potassium hydroxide.
(b) Discuss what happened in this reaction as the potassium hydroxide was added to the sulfuric acid. In your answer you should:
• relate the colours of the solution observed to the acidity and pH of the solution
• explain why the different colours of the solution were produced AND link these colours to the ions present during the reaction.
• explain the advantages of using universal indicator compared to litmus paper.
2)Experiment One
A student carried out an experiment in the lab using the following method:
Step one: Universal indicator was added to a solution of hydrochloric acid in a beaker.
Step two: Calcium hydroxide was added slowly until the solution turned green.
Step three: The contents of the beaker were then poured into an evaporating dish and left in a sunny place for several days.
(a) Write a scientific aim for this experiment.
(b) Explain the purpose of each step in the method and how the equipment and chemicals used achieve that purpose.
Experiment Two
In another experiment the following method was used:
Step one: A beaker was placed on a balance as shown in the diagram below.
Step two: Hydrochloric acid was added to solid sodium carbonate in the beaker.
Step three: The mass was recorded over time.
(c) Write a word equation AND a balanced symbol equation for the reaction between hydrochloric acid and sodium carbonate.
(d) Explain why the mass of the beaker and contents would decrease over time.
1) Two beakers are shown below. Beaker one contains sulfuric acid solution and 5 drops of universal indicator. Beaker two contains pure water and 5 drops of universal indicator. Sodium hydroxide solution was added to both beakers until no more changes were observed.
a) Write a word equation AND a balanced symbol equation for the reaction between sulfuric acid and sodium hydroxide.b) What is the colour of universal indicator in each solution at the start?c) Describe the colour changes as sodium hydroxide solution is added to each beaker, AND explain what this tells you about the changing pH of each solution.d) Explain the relationship between the pH of the solutions and the ions in the solutions, as the sodium hydroxide is added to each of the beakers
2) A student wanted to make the neutral salt, sodium nitrate
a) Explain how to make sodium nitrate by mixing sodium carbonate and nitric acid solutions using school laboratory equipment (your explanation may use notes and diagrams).
b) Explain how litmus paper could be used during the process described to show the salt being produced is neutral.
c) Write a word equation AND a balanced symbol equation for the reaction between sodium carbonate and nitric acid.
1) A student put 10 ml of dilute nitric acid in a boiling tube with five drops of universal indicator. Sodium hydroxide of the same concentration was then added. The following observations were recorded.
Discuss the reaction occurring as sodium hydroxide is added to the nitric acid. In your answer you should:
• explain the relationship between the colours observed and the pH of the solution
• explain which ions cause the different colours of the solution
• write a word equation for the reaction AND a balanced symbol equation for the reaction.
2) A student wanted to make the salt, magnesium chloride. Discuss how the student would make magnesium chloride salt from hydrochloric acid and magnesium oxide.
In your answer you should:
• state what type of reaction occurs
• write a word equation AND a balanced symbol equation for the reaction between hydrochloric acid and magnesium oxide
• explain how you would make magnesium chloride in a school lab from hydrochloric acid and solid magnesium oxide (include labelled diagrams).
A student puts 5mL of dilute hydrochloric acid into a boiling tube and adds five drops of universal indicator to the solution. The student then takes a solution of sodium hydroxide of the same concentration as the acid and adds it one drop at a time to the acid until the colour stops changing.
a) i) Describe the colour of the universal indicator solution:
in the hydrochloric acid before any sodium hydroxide was added.
when the sodium hydroxide was added and the colour of the solution stopped changing.
ii)As the sodium hydroxide is added several colour changes occur. Explain how the colour changes relate to pH AND what ions are present in the solution colour changes.
b) The student combines equal volumes of nitric acid solution and sodium carbonate solution. Both solutions have the same concentration. Discuss what happens in this reaction. In your answer, you should:
name the type of reaction involved and the ions involved
describe what the student would observe
state the products of the reaction and link these to the observations made
write a word equation for the reaction
write a balanced symbol equation for the reaction.
A student reacted dilute sulfuric acid solution with solid sodium hydrogen carbonate. Discuss the reasons for any observations the student would make for this reaction. In your answer you should:
• Describe any observations the student would make for this reaction.
• Write a word equation and balanced symbol equation for the reaction of sulfuric acid with sodium hydrogen carbonate.
• Explain how the observations link to the products formed.
1) A student carried out an experiment to neutralise sulfuric acid by adding sodium hydroxide to it.
Discuss how the student could have determined when the sulfuric acid had been neutralised and what effect adding the sodium hydroxide has on the pH of the solution.
In your answer include:
• an explanation of neutralisation in terms of an acid-base reaction
• the name of the indicator used
• observations that the student would make as the sodium hydroxide is added to the acid
• a word and balanced chemical equation for the reaction.
2) A student reacted zinc oxide with sulfuric acid, and wrote the following incorrect equation to represent the reaction:
ZnO2 + H2SO4 → 2H2O + ZnSO4 + H2
The equation contains THREE errors.
a) Rewrite the equation so that it is a correctly balanced chemical equation.
b) Discuss the reasons for the three changes made to correctly balance the chemical equation.
An important part of keeping swimming pools safe is to keep the pH of the water balanced in the range 7.0 to 7.6.
Three chemicals used in pools are chlorine compounds (that react with water to produce hydrochloric acid), sodium hydrogen carbonate and aluminium sulfate.
a) Complete the following table to show the characteristics of the solutions listed in the table below.
An important part of keeping swimming pools safe is to keep the pH of the water balanced in the range 7.0 to 7.6.
Three chemicals used in pools are chlorine compounds (that react with water to produce hydrochloric acid), sodium hydrogen carbonate and aluminium sulfate.
b) Complete the following table to show the characteristics of the solutions listed in the table below.
1) a) State the colour seen if red litmus and blue litmus are added to separate samples of the following solutions.
b) Write down the pH value that best represents the pH value of pure water, sodium hydroxide and hydrochloric acid
2) Copper sulfate is a salt. Copper sulfate crystals can be prepared in the laboratory by adding copper oxide to an acid.
a) Name the acid that would be used to make copper sulfate crystals and explain your choice.
b) Write a word equation for the reaction of copper oxide and the acid.
c) Hydrochloric acid is added to a sodium carbonate solution. Describe the observation(s) that would be made when this reaction occurs, and explain the reason for them.
d) Write a balanced chemical equation for the reaction between hydrochloric acid and sodium carbonate solution.
1) a) The pH values of three substances are given below:
Hydrochloric acid pH = 1
Potassium carbonate solution pH = 9
Sodium hydroxide solution pH = 14
When Universal Indicator solution is added to each of the substances listed above , what colour would result?
b) Potassium carbonate solution is added slowly to the hydrochloric acid (without indicator) in a beaker until no further change is seen.
i) Describe what you would see happening when potassium carbonate is added to the acid.
ii) Write a balanced chemical equation for the reaction between potassium carbonate and hydrochloric acid.
c) In another experiment, sodium hydroxide solution is added slowly to the hydrochloric acid to which Universal Indicator solution has been added.
i) Describe how the colour of the Universal Indicator solution changes as the sodium hydroxide solution is added.
ii) Discuss how the colour changes relate to the substances present in the solution. Use the substances from the key list: water, sodium chloride, sodium hydroxide, hydrochloric acid
2) Epsom salt has the chemical formula MgSO4. It can be prepared by reacting an acid with magnesium hydroxide.
a) i) Give the chemical name for MgSO4
ii) Name the acid used in this reaction
b) Write the word equation for the preparation of MgSO4.
c) This reaction is described as a neutralisation reaction. Explain what is meant by the term neutralisation.
1) James carried out an investigation to see how many colours he could make with universal indicator. He started with 5 mL of dilute hydrochloric acid in a boiling tube and added 5 drops of universal indicator. The solution turned red. James then added dilute sodium hydroxide to the boiling tube, a drop at a time, until the solution turned purple.
i) James obtained three more colours as he added the sodium hydroxide to the acid. These colours were green, blue and yellow. Write the colours in the correct order as they appeared.
ii) Which colour on the chart corresponds to a pH of 1–2?
iii) Discuss what effect adding the sodium hydroxide has on the pH of the solution in the boiling tube.
2) a) i) A student has one test tube containing magnesium oxide and another containing magnesium carbonate. Both substances are white powders.
The student has to identify which test tube contains magnesium oxide and which test tube contains magnesium carbonate, using only sulfuric acid.
Explain how the student would do this.
ii) Magnesium hydroxide also reacts with sulfuric acid. Write a balanced symbol equation for this reaction.
1) a) Write down the colour of the following substance with i) Universal Indicator and ii) litmus paper
Hydrochloric acid
Calcium oxide
b) i) Name the most strongly alkaline substance shown above.
ii) Which fruit juice is more acidic than vinegar?
iii) Bacteria can turn sugar in your mouth to acid that attacks teeth. Explain why toothpaste has such a high pH.
2) i) Hydrochloric and sulfuric acids both react with carbonates and hydrogen carbonates to produce a gas. Name the gas.
ii) Write the word equation for the reaction of hydrochloric acid with copper carbonate.
iii) Write a fully balanced symbol equation for the reaction of sulfuric acid with sodium hydrogen carbonate.
iv) Explain why the reactions of acids with carbonates and hydrogen carbonates are called neutralisation reactions.
to help with your understanding of Rates of Reaction
Use SOLO Taxonomy
and
this Rates of Reaction weebly
to help you to learn how to
structure your NCEA Answer
to a question explaining Rates of Reaction.
NCEA PAST EXAM QUESTION: Rates of Reaction and particle theory
(a) Calcium carbonate pieces are placed in a flask and hydrochloric acid is added. Immediately a balloon is placed over the top of the flask. The balloon then starts to inflate.
(i) Explain why the balloon inflates.
In a second experiment, the same mass of calcium carbonate in a powdered form is used.
(ii) Explain why the balloon inflates faster when powdered calcium carbonate is used.
(b) Using the same chemical substances (calcium carbonate and hydrochloric acid), discuss a different way to make the balloon inflate faster.
In your answer you should refer to rates of reaction and particle collisions.
1) The table below shows the size of marble chips (calcium carbonate) used in a chemical investigation into factors affecting rate of reaction.
Experiment 1: 10 mL of hydrochloric acid was added to a boiling tube containing small marble chips.
Experiment 2: 10 mL of hydrochloric acid of the same concentration as in Experiment 1 was added to another boiling tube containing large marble chips.
In both experiments the total mass of the marble chips was the same.
The boiling tubes were connected to an inverted measuring cylinder in a basin of water, as shown in the diagram below.
(a) State what factor affecting the rate of reaction is being investigated in this experiment.
(b) Explain what is happening in Experiment 1 in sections A, B, and C of the graph in terms of reaction rate. In your answer you should refer to particle collisions.
(c) Explain why Experiment 1 was faster than Experiment 2.
In your answer you should:
• explain how the graph shows that Experiment 1 is faster
• explain how the size of the marble chips affects the number of particle collisions.
In your answer you should:
• state any other observations that would be made as hydrochloric acid reacts with the sodium carbona
• explain how the products formed by the reaction lead to the decrease in mass of the beaker and conte
The following experiment was carried out at 20°C and then repeated at 40°C.Marble chips (calcium carbonate) were added to hydrochloric acid in a conical flask. The mass and size of marble chips, and the concentration and volume of hydrochloric acid used, were the same for both experiments. The flask was connected to an inverted measuring cylinder in a basin of water, as shown in the diagram below.
The volume of gas produced at the two different temperatures was measured for a few minutes and the results were used to sketch the graph shown below.
State which line on the graph represents the reaction at 40°C and explain how you worked this out. In your answer you should:• identify which line represents the reaction at 40°C• explain why the line you have identified is the reaction at 40°C• give reasons for the different rates of reaction in terms of particles• explain why both lines end up horizontal.
Calcium carbonate (marble chips) and hydrochloric acid react together in a conical flask. The word equation for this reaction is:
calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide gas
(a) Describe an observation you would make when this reaction occurs.
The mass of the flask and contents is measured on a scale over time and recorded on the graph shown below.
(b) Explain why the mass decreases with time. In your answer you should:
• consider all the products being formed
• explain what is happening, in terms of particles AND the rate of reaction, in each section of the graph.
(c) When more concentrated hydrochloric acid is used, the reaction is faster.
Explain the difference in the rate of reaction. In your answer you should refer to:
• particles
• collisions
• reaction rate.
Marble chips (calcium carbonate) are added to dilute hydrochloric acid in a conical flask. The flask is connected to an inverted measuring cylinder in a trough of water, as shown in the diagram below. The volume of gas produced is measured over a few minutes, and the results used to sketch a graph.
(a) The slope of the graph is steep at the beginning and then levels off over time. Explain what is happening, in terms of particles, during the reaction.
(b) Complete the word and symbol equations below to show the reaction in the experiment.
(c) The experiment is repeated but this time the same mass of marble chips is crushed into a powder before it is added to the flask.
Discuss the effect on the reaction rate of using powdered marble with hydrochloric acid compared with using marble chips. In your answer, you should:
compare the rates of reaction
explain the differences in the reaction rate by discussing how crushing the marble chips affects the number of particle collisions.
GRAB YOUR CALCULATOR, NCEA RESOURCE BOOK AND TWO PENS (ONE SPARE!)FIND A QUIET DESK FOR 1 HOURNO MOBILES, NO LAPTOPS, NO DISTRACTIONSDO YOUR BEST EFFORT AT THE ACIDS & BASES SECTION OF THE FREE SciPAD EXAM BELOW
ATOMIC STRUCTURE
NCEA PAST EXAM QUESTIONS on Atomic structure
(a) Complete the table below.
(b) Write the formulae for the following ionic compounds. Use the table of ions in your resource booklet.
(i) Silver fluoride
(ii) Potassium sulfate
(iii) Calcium nitrate
(c) Sodium burns in oxygen gas, O2, to form sodium oxide, Na2O.
(i) Explain how the Na and O atoms form Na+ and O2– ions, in terms of their groups in the periodic table, electron arrangement, AND number of protons.
(ii) Justify the ratio of Na+ and O2– ions in the formula Na2O, in terms of the electrons lost or gained, and
the charge on each ion. Include an explanation of the type of bonding between the Na+ and O2– ions.
The diagrams below show models of three different atoms.
(a) Each of these atoms can form ions, as listed below.
• Explain why each of the ions has the charge it does, in terms of electron arrangement and number of protons.
• Ions are charged atoms. Explain how each of the ions below reached the charge shown.
You should discuss particles gained or lost by the atoms involved, and the reasons for this.
Aluminium ion, Al3
Sulfide ion, S2–
Chloride ion, Cl–
(b) Explain why an ionic bond would not form between a sulfide ion and a chloride ion
In your answer you should:
• describe an ionic bond
• refer to charges and electron arrangements of the ions involved.
(i) Calcium chloride
(ii) Sodium nitrate
(iii) Zinc nitrate
(b) Complete the table below for the ions formed by magnesium, aluminium, and oxygen. Use the periodic table in your Resource Booklet to help you.
(c) The formula for magnesium oxide is MgO. The formula for aluminium oxide is Al2O3. Explain why the two formulae are different. In your answer:
• consider the ratio of ions in each formula and explain how the ratio is related to the charge on the ions
• relate the ratio of ions in the formula to the number of electrons lost or gained by each atom.
F–, Ne, and Mg2+have the same electron arrangement.
(a) Complete the table below
(b) Compare the atomic structure of F–, Ne, and Mg2+ In your answer you should:
• describe the difference between an atom and an ion
• explain the charges on F–, Ne, and Mg2+in terms of electron arrangement and number of protons
• relate the position of F–, Ne, and Mg2+on the periodic table to the charges and electron arrangement
• explain why all three have the same electron arrangement.
a) State the charges of ALL three ions, Ca2+, F- and K+ in terms of electron arrangement and number of protons.
b) Use their positions on the periodic table to explain why two of the atoms form ions with the same charge, AND two of the atoms form ions with the same electron arrangement.
a) Explain why the ions formed by sodium and oxygen both have the same electron arrangement. In your answer you should:
• describe an ion
• describe the atomic structures of a sodium ion and an oxide ion
• state the charge on the sodium ion and the oxide ion
• explain the charges on both ions in terms of electron arrangement and number of protons.
b) Element X is between numbers 11 and 18 on the Periodic Table. An atom of element X forms an ion. This ion combines with the hydroxide ion to form a neutral compound, X(OH)3. Determine what element X is and justify your answer. In your answer you should:
• consider the ratio of X ions to hydroxide ions
• use the formula X(OH)3 to determine the charge of the X ion
• explain how you would use the Periodic Table in your Resource Booklet to find out which group element X is in
• name element X.
a) Magnesium and calcium atoms both form ions with a charge of +2. Magnesium atoms form Mg2+ ions, and calcium atoms form Ca2+ ions.
Explain why magnesium and calcium atoms form ions with the same charge of +2. In your answer, you should:
define an ion
explain why atoms form ions
identify the group on the periodic table where the two atoms are found
explain why both magnesium and calcium ions have a charge of +2.
b) Sodium and beryllium atoms form ions with different charges. Complete the table below.
c) Explain why the ions in sodium hydroxide combine to give the formula NaOH but the ions in beryllium hydroxide combine to give the formula Be(OH)2.
In your answer, you should:
compare the charges on the individual ions found in the compounds sodium hydroxide and beryllium hydroxide
explain why the ions combine in the ratios the way they do to form the compounds NaOH and Be(OH)2.
d) Explain why Li is a neutral atom. In your answer, you should fully describe its atomic structure and state the electron configuration.
Aluminium reacts with oxygen to form aluminium oxide. The formula of aluminium oxide contains two aluminium ions and three oxide ions. Discuss why the formula has two aluminium ions and three oxide ions. In your answer you should:
• State the formula for aluminium oxide.
• State the electron configuration of the aluminium atom, the oxygen atom, the aluminium ion, and the oxide ion.
• Use the electron configurations and numbers of electrons lost or gained when forming ions to justify the formula of aluminium oxide.
You may support your answer with diagrams.
a) Explain why carbon (C12) is a neutral atom. You should describe the atomic structure, and state the electron configuration.
b) Explain how the particles within an atom contribute to its overall mass.
c) Discuss how the mass of nitrogen (N13) compares with carbon (C12).
a) Oxygen atoms are made of protons, neutrons, and electrons. One type of oxygen atom can be represented as 818O.
i) Draw a diagram to show the arrangement of the electrons, protons, and neutrons within the above oxygen atom:
ii) Explain, with reference to the diagram, why the atom is neutral.
b) Use the table of ions in the Resource Booklet to fill in the missing name or formula for each of the compounds below.
c) Both potassium and magnesium form compounds with hydroxide ions.
i) Complete the table below for potassium and magnesium:
ii) Discuss why potassium hydroxide has the formula KOH, while magnesium hydroxide has the formula Mg(OH)2. Refer to:
• the information in part (i)
• the changes in the electron arrangements of potassium and magnesium when they react.
a) The element potassium can be represented as shown below.
i) How many protons, electrons and neutrons are in the element potassium shown above?
ii) Name the two particles found in the nucleus.
iii) The electron arrangement for the element carbon can be written 2, 4 Write the electron arrangement for the element potassium
b)i) Give the formula of zinc oxide potassium sulfate calcium hydrogen carbonate
ii) Name the following compounds Cu(OH)2 PbS MgCl2
c)i) State the charge on the iron ion in the compounds Fe2O3 FeCl2 Fe2(CO3)3
ii) Explain why the charge on the ion of element X in X(OH)2 is 2+.
The diagram below represents a model of a magnesium atom
The symbols in the diagram above represent the proton, electron and neutron.
a) Write the appropriate symbol from the diagram and what it represents - proton, electron or neutron
b) i) Using similar symbols, draw a diagram that shows a sodium atom
ii) Discuss the similarities and differences between a sodium atom and a sodium ion. You should consider the number of protons, electrons and neutrons, and the charge of each particle.
c) Name the compound Pb(NO3)-2 Refer to the Table of Ions in the Resource Booklet
d) Write the formula for potassium sulfide
e) i) How many atoms are there in Al(OH)3?
ii) How many atoms are there in 2Al(OH)3?
a) The diagram below can be used to represent the arrangement of electrons in levels around the nucleus of a sodium atom.
i) The atomic number of sodium is 11. How many protons are there in the nucleus of the neutral atom?
ii) How many neutrons are there in a sodium atom with a mass number of 23?
iii) How many electrons does a sodium atom lose to form a sodium ion?
b) A neutral oxygen atom has 8 electrons in the arrangement 2,6.
i) What is the atomic number of oxygen?
ii) How many electrons does oxygen gain to form an oxide ion?
iii) Draw a diagram like the one above for the arrangement of electrons around the nucleus of an oxide ion.
c) The formula of aluminium oxide is Al2O3. Explain why the formula has two aluminium atoms for every three oxygen atoms.
d) Use the table of ions in the Resource Booklet to work out the formulae for the following compounds.
Potassium oxide Magnesium nitrate Calcium sulfide Ammonium sulfate
e) Name these compounds: CuCl2 Zn(OH)2 KF
f) Refer to the positions of oxygen and fluorine in the Periodic Table provided in the Resource Booklet. Comparing oxygen and fluorine, discuss how the electron arrangement, the atoms’ positions in the Periodic Table and the charges on their ions are related.
a) Complete the table below by putting the appropriate numbers in the boxes (i) – (vi).
b) The electron arrangement for nitrogen (N) is 2,5. Write the electron arrangement for: Li P Mg2+
c) Compare the positions of sodium (Na), potassium (K) and rubidium (Rb) on the Periodic Table.
i) What is the charge on a rubidium ion? (ii) Explain your answer.
d) i) How many atoms of oxygen are there in the formula Mg(HCO3)2? What is the total number of atoms in the formula?
ii) Using the Table of Ions provided in your Resource Booklet, write formulae for: calcium oxide, copper hydroxide, sodium carbonateiii) Name each of these compounds: MgO, Na2S, Ca(NO3)2
e) The doctor told Miriam she was tired and pale because she was low in iron. The iron tablets Miriam was given to take did not look like the iron nails they used in woodwork. Discuss how the chemical differences between the iron in the tablets and the iron in the nails are related to their uses.
There are a few different activities below to help re-inforce your understanding
EXTRA HELP questions with answers on atomic structure
EXTRA HELP Periodic table with element symbols and names
NZQA Resource Book: You WILL be given this with your Exam Paper
EXTRA HELP complete the blank periodic table of shells to practice drawing/comparing/contrasting electron configuration of atoms
ANSWERS are on the periodic table animation of shells
EXTRA HELP: a straightforward animation explaining the formation of NaCl, a video too
EXTRA HELP questions on ions to help you visualise and describe ionic charges clearly
INTERACTIVE animation to practice creating ionic compounds
RE-INFORCE and EXTEND your thinking and understanding of ionic bonding, with answers too
THINKING SKILLS: test your logical thinking skills and knowledge of atoms of ions on the Alien Periodic table, with answers too
PROPERTIES AND USES OF ACIDS AND BASES
NCEA PAST EXAM QUESTIONS on Properties and Uses of Acids and Bases
1) Write a word equation AND a balanced symbol equation for the reaction between calcium carbonate and hydrochloric acid.
2) A student has three unlabelled beakers each containing a colourless liquid. One contains water, one contains a solution of baking soda (sodium hydrogen carbonate), and one contains white vinegar (a solution of ethanoic acid).
To work out which liquid is which, the student put a drop from each beaker onto a piece of blue litmus paper and a piece of red litmus paper. She then added universal indicator to each beaker. The following results were obtained:
(a) Complete the last column of the table above to identify the three liquids.
(b) Use the information in the table to show how each of the liquids can be identified. In your answer you should:
• use all of the observations for each beaker
• state the approximate pH from the colour of the universal indicator.
(c) Another student was given two beakers (Beaker 4 and Beaker 5) each containing different liquids. The liquid in Beaker 4 had a pH of 1. The liquid in Beaker 5 had a pH of 6. Discuss which liquid is more acidic and how you know this. In your answer you should:
• use the pH to determine which liquid is more acidic
• compare the amount of hydrogen ions AND hydroxide ions in Beaker 4 (pH 1) with the amount of hydrogen ions AND hydroxide ions in Beaker 5 (pH 6).
3) A beaker contains sodium hydroxide solution and 5 drops of universal indicator. Sulfuric acid was added to the beaker until no more changes were observed.
(a) Write a word equation AND a balanced symbol equation for the reaction between sulphuric acid and sodium hydroxide.
(b) Describe how the indicator colour changes as the sulfuric acid is added to the beaker, AND explain what this tells you about the changing pH of this solution.
(c) Explain the relationship between the changing pH of the solution and the ions in the solution as the sulfuric acid is added to the beaker.
Potassium hydroxide (KOH) was added to a solution of sulfuric acid containing universal indicator until no further change was observed. The experiment was repeated, but a piece of red litmus paper and a piece of blue litmus paper were each dipped into the solution after each 5 mL of potassium hydroxide was added. The results of the experiments are shown in the table below.
(a) Write a word equation AND a balanced symbol equation for the reaction between sulfuric acid and potassium hydroxide.
(b) Discuss what happened in this reaction as the potassium hydroxide was added to the sulfuric acid. In your answer you should:
• relate the colours of the solution observed to the acidity and pH of the solution
• explain why the different colours of the solution were produced AND link these colours to the ions present during the reaction.
• explain the advantages of using universal indicator compared to litmus paper.
2) Experiment One
A student carried out an experiment in the lab using the following method:
Step one: Universal indicator was added to a solution of hydrochloric acid in a beaker.
Step two: Calcium hydroxide was added slowly until the solution turned green.
Step three: The contents of the beaker were then poured into an evaporating dish and left in a sunny place for several days.
(a) Write a scientific aim for this experiment.
(b) Explain the purpose of each step in the method and how the equipment and chemicals used achieve that purpose.
Experiment Two
In another experiment the following method was used:
Step one: A beaker was placed on a balance as shown in the diagram below.
Step two: Hydrochloric acid was added to solid sodium carbonate in the beaker.
Step three: The mass was recorded over time.
(c) Write a word equation AND a balanced symbol equation for the reaction between hydrochloric acid and sodium carbonate.
(d) Explain why the mass of the beaker and contents would decrease over time.
1) Two beakers are shown below. Beaker one contains sulfuric acid solution and 5 drops of universal indicator. Beaker two contains pure water and 5 drops of universal indicator. Sodium hydroxide solution was added to both beakers until no more changes were observed.
2) A student wanted to make the neutral salt, sodium nitrate
a) Explain how to make sodium nitrate by mixing sodium carbonate and nitric acid solutions using school laboratory equipment (your explanation may use notes and diagrams).
b) Explain how litmus paper could be used during the process described to show the salt being produced is neutral.
c) Write a word equation AND a balanced symbol equation for the reaction between sodium carbonate and nitric acid.
1) A student put 10 ml of dilute nitric acid in a boiling tube with five drops of universal indicator. Sodium hydroxide of the same concentration was then added. The following observations were recorded.
Discuss the reaction occurring as sodium hydroxide is added to the nitric acid. In your answer you should:
• explain the relationship between the colours observed and the pH of the solution
• explain which ions cause the different colours of the solution
• write a word equation for the reaction AND a balanced symbol equation for the reaction.
2) A student wanted to make the salt, magnesium chloride. Discuss how the student would make magnesium chloride salt from hydrochloric acid and magnesium oxide.
In your answer you should:
• state what type of reaction occurs
• write a word equation AND a balanced symbol equation for the reaction between hydrochloric acid and magnesium oxide
• explain how you would make magnesium chloride in a school lab from hydrochloric acid and solid magnesium oxide (include labelled diagrams).
A student puts 5mL of dilute hydrochloric acid into a boiling tube and adds five drops of universal indicator to the solution. The student then takes a solution of sodium hydroxide of the same concentration as the acid and adds it one drop at a time to the acid until the colour stops changing.
a) i) Describe the colour of the universal indicator solution:
in the hydrochloric acid before any sodium hydroxide was added.
when the sodium hydroxide was added and the colour of the solution stopped changing.
ii) As the sodium hydroxide is added several colour changes occur. Explain how the colour changes relate to pH AND what ions are present in the solution colour changes.
b) The student combines equal volumes of nitric acid solution and sodium carbonate solution. Both solutions have the same concentration. Discuss what happens in this reaction. In your answer, you should:
name the type of reaction involved and the ions involved
describe what the student would observe
state the products of the reaction and link these to the observations made
write a word equation for the reaction
write a balanced symbol equation for the reaction.
A student reacted dilute sulfuric acid solution with solid sodium hydrogen carbonate. Discuss the reasons for any observations the student would make for this reaction. In your answer you should:
• Describe any observations the student would make for this reaction.
• Write a word equation and balanced symbol equation for the reaction of sulfuric acid with sodium hydrogen carbonate.
• Explain how the observations link to the products formed.
1) A student carried out an experiment to neutralise sulfuric acid by adding sodium hydroxide to it.
Discuss how the student could have determined when the sulfuric acid had been neutralised and what effect adding the sodium hydroxide has on the pH of the solution.
In your answer include:
• an explanation of neutralisation in terms of an acid-base reaction
• the name of the indicator used
• observations that the student would make as the sodium hydroxide is added to the acid
• a word and balanced chemical equation for the reaction.
2) A student reacted zinc oxide with sulfuric acid, and wrote the following incorrect equation to represent the reaction:
ZnO2 + H2SO4 → 2H2O + ZnSO4 + H2
The equation contains THREE errors.
a) Rewrite the equation so that it is a correctly balanced chemical equation.
b) Discuss the reasons for the three changes made to correctly balance the chemical equation.
An important part of keeping swimming pools safe is to keep the pH of the water balanced in the range 7.0 to 7.6.
Three chemicals used in pools are chlorine compounds (that react with water to produce hydrochloric acid), sodium hydrogen carbonate and aluminium sulfate.
a) Complete the following table to show the characteristics of the solutions listed in the table below.
An important part of keeping swimming pools safe is to keep the pH of the water balanced in the range 7.0 to 7.6.
Three chemicals used in pools are chlorine compounds (that react with water to produce hydrochloric acid), sodium hydrogen carbonate and aluminium sulfate.
b) Complete the following table to show the characteristics of the solutions listed in the table below.
1) a) State the colour seen if red litmus and blue litmus are added to separate samples of the following solutions.
b) Write down the pH value that best represents the pH value of pure water, sodium hydroxide and hydrochloric acid
2) Copper sulfate is a salt. Copper sulfate crystals can be prepared in the laboratory by adding copper oxide to an acid.
a) Name the acid that would be used to make copper sulfate crystals and explain your choice.
b) Write a word equation for the reaction of copper oxide and the acid.
c) Hydrochloric acid is added to a sodium carbonate solution. Describe the observation(s) that would be made when this reaction occurs, and explain the reason for them.
d) Write a balanced chemical equation for the reaction between hydrochloric acid and sodium carbonate solution.
1) a) The pH values of three substances are given below:
Hydrochloric acid pH = 1
Potassium carbonate solution pH = 9
Sodium hydroxide solution pH = 14
When Universal Indicator solution is added to each of the substances listed above , what colour would result?
b) Potassium carbonate solution is added slowly to the hydrochloric acid (without indicator) in a beaker until no further change is seen.
i) Describe what you would see happening when potassium carbonate is added to the acid.
ii) Write a balanced chemical equation for the reaction between potassium carbonate and hydrochloric acid.
c) In another experiment, sodium hydroxide solution is added slowly to the hydrochloric acid to which Universal Indicator solution has been added.
i) Describe how the colour of the Universal Indicator solution changes as the sodium hydroxide solution is added.
ii) Discuss how the colour changes relate to the substances present in the solution. Use the substances from the key list: water, sodium chloride, sodium hydroxide, hydrochloric acid
2) Epsom salt has the chemical formula MgSO4. It can be prepared by reacting an acid with magnesium hydroxide.
a) i) Give the chemical name for MgSO4
ii) Name the acid used in this reaction
b) Write the word equation for the preparation of MgSO4.
c) This reaction is described as a neutralisation reaction. Explain what is meant by the term neutralisation.
1) James carried out an investigation to see how many colours he could make with universal indicator. He started with 5 mL of dilute hydrochloric acid in a boiling tube and added 5 drops of universal indicator. The solution turned red. James then added dilute sodium hydroxide to the boiling tube, a drop at a time, until the solution turned purple.
i) James obtained three more colours as he added the sodium hydroxide to the acid. These colours were green, blue and yellow. Write the colours in the correct order as they appeared.
ii) Which colour on the chart corresponds to a pH of 1–2?
iii) Discuss what effect adding the sodium hydroxide has on the pH of the solution in the boiling tube.
2) a) i) A student has one test tube containing magnesium oxide and another containing magnesium carbonate. Both substances are white powders.
The student has to identify which test tube contains magnesium oxide and which test tube contains magnesium carbonate, using only sulfuric acid.
Explain how the student would do this.
ii) Magnesium hydroxide also reacts with sulfuric acid. Write a balanced symbol equation for this reaction.
1) a) Write down the colour of the following substance with i) Universal Indicator and ii) litmus paper
Hydrochloric acid
Calcium oxide
b) i) Name the most strongly alkaline substance shown above.
ii) Which fruit juice is more acidic than vinegar?
iii) Bacteria can turn sugar in your mouth to acid that attacks teeth. Explain why toothpaste has such a high pH.
2) i) Hydrochloric and sulfuric acids both react with carbonates and hydrogen carbonates to produce a gas. Name the gas.
ii) Write the word equation for the reaction of hydrochloric acid with copper carbonate.
iii) Write a fully balanced symbol equation for the reaction of sulfuric acid with sodium hydrogen carbonate.
iv) Explain why the reactions of acids with carbonates and hydrogen carbonates are called neutralisation reactions.
RATES OF REACTION AND PARTICLE THEORY
Try this marble chips simulation
this is a .dcr file, 1st update Adobe Shockwave then
2nd change your options to open the simulation in your browser
and
set of questions
marblechipsimulation.docx
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- 31 KB
to help with your understanding of Rates of Reaction
Use SOLO Taxonomy
and
this Rates of Reaction weebly
to help you to learn how to
structure your NCEA Answer
to a question explaining Rates of Reaction.
NCEA PAST EXAM QUESTION: Rates of Reaction and particle theory
(a) Calcium carbonate pieces are placed in a flask and hydrochloric acid is added. Immediately a balloon is placed over the top of the flask. The balloon then starts to inflate.
(i) Explain why the balloon inflates.
In a second experiment, the same mass of calcium carbonate in a powdered form is used.
(ii) Explain why the balloon inflates faster when powdered calcium carbonate is used.
(b) Using the same chemical substances (calcium carbonate and hydrochloric acid), discuss a different way to make the balloon inflate faster.
In your answer you should refer to rates of reaction and particle collisions.
1) The table below shows the size of marble chips (calcium carbonate) used in a chemical investigation into factors affecting rate of reaction.
Experiment 1: 10 mL of hydrochloric acid was added to a boiling tube containing small marble chips.
Experiment 2: 10 mL of hydrochloric acid of the same concentration as in Experiment 1 was added to another boiling tube containing large marble chips.
In both experiments the total mass of the marble chips was the same.
The boiling tubes were connected to an inverted measuring cylinder in a basin of water, as shown in the diagram below.
(a) State what factor affecting the rate of reaction is being investigated in this experiment.
(b) Explain what is happening in Experiment 1 in sections A, B, and C of the graph in terms of reaction rate. In your answer you should refer to particle collisions.
(c) Explain why Experiment 1 was faster than Experiment 2.
In your answer you should:
• explain how the graph shows that Experiment 1 is faster
• explain how the size of the marble chips affects the number of particle collisions.
In your answer you should:
• state any other observations that would be made as hydrochloric acid reacts with the sodium carbona
• explain how the products formed by the reaction lead to the decrease in mass of the beaker and conte
The following experiment was carried out at 20°C and then repeated at 40°C.Marble chips (calcium carbonate) were added to hydrochloric acid in a conical flask. The mass and size of marble chips, and the concentration and volume of hydrochloric acid used, were the same for both experiments. The flask was connected to an inverted measuring cylinder in a basin of water, as shown in the diagram below.Calcium carbonate (marble chips) and hydrochloric acid react together in a conical flask. The word equation for this reaction is:
calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide gas
(a) Describe an observation you would make when this reaction occurs.
The mass of the flask and contents is measured on a scale over time and recorded on the graph shown below.
(b) Explain why the mass decreases with time. In your answer you should:
• consider all the products being formed
• explain what is happening, in terms of particles AND the rate of reaction, in each section of the graph.
(c) When more concentrated hydrochloric acid is used, the reaction is faster.
Explain the difference in the rate of reaction. In your answer you should refer to:
• particles
• collisions
• reaction rate.
Marble chips (calcium carbonate) are added to dilute hydrochloric acid in a conical flask. The flask is connected to an inverted measuring cylinder in a trough of water, as shown in the diagram below. The volume of gas produced is measured over a few minutes, and the results used to sketch a graph.
(a) The slope of the graph is steep at the beginning and then levels off over time. Explain what is happening, in terms of particles, during the reaction.
(b) Complete the word and symbol equations below to show the reaction in the experiment.
(c) The experiment is repeated but this time the same mass of marble chips is crushed into a powder before it is added to the flask.
Discuss the effect on the reaction rate of using powdered marble with hydrochloric acid compared with using marble chips. In your answer, you should:
compare the rates of reaction
explain the differences in the reaction rate by discussing how crushing the marble chips affects the number of particle collisions.
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